COSMOGENIC Mn$sup 53$, Al$sup 26$, AND Be$sup 10$ IN IRON METEORITES AND A SEARCH FOR TERRESTRIAL Mn$sup 5$$sup 3$
Three long-lived radionuclides, Al/sup 26/ (t/sub 1/2/ = 8 x 10/sup 5/ yr), Be/sup 10/ (t/sub 1/2/ =2.7 x 10/sup 6/ yr), and Mn/sup 53/ (t/sub 1/2/ 1.3x 10/ sup 53/ yr), were isolated from three iron meteorites, and their specific activities determined with a BETA flow counter. Radiochemical purification was performed. An absorption curve was determined for the Al/sup 26/ and Be/sup 10/ samples from one of the meteorites as a further criterion for radiochemical purity. The gamma activity of the Mn/sup 53/ samples was found to be negligible, assuring that they were not contaminated with Mn/sup 54/. The production rates of a number of nuclides, both stable and radioactive, in an iron meteorite were calculated. The integral star size distribution in iron, produced by cosmic rays, was measured and approximated by the expression N/sub p/ = e/sup -BP/, where p was the number of prongs for a given star. Assuming that only singly (83%) and doubly (17%) charged prongs were produced, the element yield per star was calculated. The isotopic yield distribution for each element produced was calculated. The absolute production rates were then calculated from measured inelastic proton cross sections and the flux of cosmic radiation. The cosmogenic star production rate as a function of depth in spherical iron meteorites was estimated from cross section-vs-depth measurements of Ar/sup 37/ production in iron by high energy protons. From these curves and the measured Be/sup 10/, Al/ sup 26/, and Mn/sup 53/ activities in the meteorites, their preatmospheric sizes were estimated. The cosmic ray exposure ages of the meteorites were calculated from the measured K/sup 40//Be/sup 10/ activity ratio compared to the predicted production ratio. Because the steady-state tritium inventory on earth may be significantly greater than can be explained by cosmic-ray production, the hypothesis of solar accretion of tritium was examined. If production of tritium in the solar corona can take place, then other simple nuclear reactions should also occur. One of these Fe/sup 56/(p alpha ) Mn/sup 53/, leads to Mn/sup 53/ production. A search for this isotope was made in manganese nodules. An estimate of the possible specific activity of Mn/sup 53/ was calculated to be 2 dpm/gm Mn. A liquid scintillation counter was used to detect the Mn/sup 53/ decays and the Mn/sup 53/ specific activity of a manganese nodule measured as -- 8.6 plus or minus 4.5 dpm/gm Mn. This result did not categorically reject the solar accretion hypothesis. (Dissertation Abstr., 22: No. 7, 1982.)
- Research Organization:
- Originating Research Org. not identified
- NSA Number:
- NSA-17-000696
- OSTI ID:
- 4777241
- Resource Relation:
- Other Information: Thesis. Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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Related Subjects
ABSORPTION
AGE ESTIMATION
ALPHA PARTICLES
ALUMINUM 26
ARGON 37
ASTROPHYSICS
BERYLLIUM 10
BETA DETECTION
COSMIC RADIATION
COSMIC RAY STARS
COUNTERS
CROSS SECTIONS
FISSION
GAMMA RADIATION
HALF-LIFE
INTERACTIONS
IRON
IRON 56
ISOTOPE SEPARATION
LIQUIDS
MANGANESE 53
MANGANESE 54
MEASURED VALUES
METEORITES
NUCLEAR REACTIONS
NUMERICALS
PARTICLE TRACKS
POTASSIUM 40
PRODUCTION
PROTONS
QUANTITY RATIO
RADIOCHEMISTRY
RADIOISOTOPES
SCINTILLATION COUNTERS
SUN
THICKNESS
TRITIUM